In small internal combustion engines utilizing a carburetor, such as those engines utilized in outdoor power equipment (e.g., a lawnmower, snowblower, etc.) cold temperature starting of the engine typically requires a more fuel-rich air-fuel mixture to sustain the combustion reaction. In some engines, this is done by closing a choke valve, thereby partially choking off the air supply to the cylinder or cylinders of the engine. As the engine warms up, the choke is no longer necessary because the increased temperatures in the engine help to sustain the combustion reaction and thus the choke is opened, allowing more air into the cylinder or cylinders for combustion.
Some carburetors utilized with small internal combustion engines include a throttle lever that engages, either directly or via an intermediate linkage, a choke lever coupled to the choke valve to actuate the choke valve. A governor is typically utilized to actuate the throttle lever and a throttle valve coupled to the throttle lever to control the speed of the engine.